Super-wide angle photographic objective

ABSTRACT

A ten group, twelve element, super-wide angle photographic objective lens which corrects chromatic aberration over the whole image plane to be used and to obtain an aberration condition balanced therewith.

1 3,738,738 11 June 12,1973

United States 7 Takahashi SUPER-WIDE ANGLE PHOTOGRAPHIC [5 6] References Cited UNITED STATES PATENTS 11/1968 Woltche................

5/1970 Woltche...

OBJECTIVE [75] Inventor: YasuoTakahashi,Tokyo,.lapan [73] Assignee: Ashai Kogaku Kogyo Kabushiki [22] Filed:

Primary ExaminerJohn K. Corbin Attorney-D. Bruce Front 211 Appl. No.: 177,343

[57] ABSTRACT A ten group, twelve element,

super-wide angle photow b m 6 mm aaw de oe Se huh c t e S d M m m 1 Chm h C6 .1 8.! m n 0 mmw lwfl .nn 6 .w m C m wflb a C .l n @m mvmm Dorm 644 7M w w 5% 3 4G" 1 .n 2 "u "n 0 U 5 n 3 mwhn u-c r Una ".6 "m I C in a.. UIF 11. 21. 218 555 [[1 3 Claims, 6 Drawing Figures SUPER-WIDE ANGLE PHOTOGRAPHIC OBJECTIVE BACKGROUND OF THE INVENTION This invention relates to wide angle photographic objective lenses. One of the drawbacks of present wide angle lenses is that with increased image angle, an overall reduction of chromatic aberration is very difficult. The wider angle the lens, the greater the aberrations. This is especially true of chromatic aberrations because the index of refraction is non-linear for different colors.

SUMMARY OF THE INVENTION The present invention relates to an optical system which corrects chromatic aberration over the whole image plane to be used and to obtain an aberration condition balanced therewith.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional, elevational view of the lens system of one embodiment of the present invention identifled hereafter as example 1;

FIG. 2 is a diagram showing the aberration curves of example 1;

FIG. 3 is a sectional, elevational view of the lens system of a second embodiment of the present invention identified hereinafter as example 2;

FIG. 4 is a diagram showing the aberration curves of example 2;

FIG. 5 is a sectional, elevational view of the lens system of a third embodiment of the present invention identified hereinafter as example 3; and

FIG. 6 is a diagram showing the aberration curves of example 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the optical system is described with reference to the three embodiments shown in FIGS. 1, 3 and 5. The discussion applies to all of FIGS. 1, 3 and 5 except where stated otherwise.

The lens 1 is of negative meniscus type with the surface of larger curvature directed to the image side; the lens 2 is of positive type; and the lens 3 and the lens 4 are of negative meniscus type with the respective surfaces of larger curvature directed to the image side. The lens 5 and the lens 6 are cemented together. The

resulting cemented lens may be of positive-negative combination as shown in FIG. I or of negative-positive combination as shown in'FIGS. 3 and 5. Also, the resulting cemented lens as a whole is characterized in that it is of low power. The lens 7 and the lens 8 are of positive type. The lens 8 is cemented to the lens 9. The lens 9 is of negative type. The lens 10 is of positive meniscus type with the surface of larger curvature directed to the image side. The lens 11 is of negative meniscus type with the surface of larger curvature directed to the image side. The lens 12 is of bi-convex positive type.

Thus, the optical system consists of a 10 group, 12 element lens.

In accordance with the present invention, the optical system is characterized by the following conditions:

, Except when the lens 5 is of positive type, then with respect to the lens 6 u 55.

The definition of terms in the above conditions are as follows:

| means absolute value;

F is the resultant focal length of the whole optical system;

F is the resultant focal length of the first to the i-th lenses;

I, is the spacing between the j-th lens and the next subsequent lens;

d is the thickness of the k-th lens;

r, is the radius of curvature of the l-th lens surface;

n, is the d-line index of refraction of the m-th lens;

v is the Abbes number of the m-th lens;

f, is the focal length of the n-th lens; and

f is the back focal length which is the length from the pole of the last lens 12 to the image forming surface.

Condition (1) is the lens power relation for obtaining f which is larger than 1.7F. This is a natural form for a type of wide angle objective optical system wherein negative lenses are introduced in the front groups for having larger f,,. If F [is smaller than F/l .3 then a much greater correction is required by the negative working surfaces R,, R, and R, and correction of coma aberration becomes difficult. Even if, as a solution to this problem, glass of greater value of index of refraction is utilized for n n; and n so that such surfaces can be of smaller curvature, since there exist only glasses of comparatively small v value (for example, if the index of refraction is greater than 1.7, then there exist only glass having 1/ which is smaller than 55) chromatic difference of magnification cannot be entirely corrected over wide-angle range so that considerable aberration remains. On the other hand, if F l is greater than F/0.7, then it is difficult to have a longer f, and the intended object cannot be attained.

The condition (2) is necessary for obtaining the intended length of f, under the condition (I). If (I, d, d, I,,) is greater than 1.1F, then the f, condition is favorable but a disadvantage is produced in that it be comes necessary to make the first lens and the front lens group larger or to make the rear lens group larger so that the peripheral light amount is increased, making correction of aberration difficult.

The condition (3) is one of the main features of the" present invention. Under condition (I), generally, chromatic aberration is overcorrected unless v, is of small value and the second lens is of very great power. With the light rays having passed through the fifth and sixth lenses, and with the negative power as indicatedby condition (5), and considering the undercorrected' whole system, it appears that excellent correction of undercorrection in the front lens group in cooperation with the action of the rear lens group.

Under the condition (4), it is desirable for attaining the object that the u difference is large. If, however, this is too much larger than 35, there is produced too much undercorrection and, accordingly, too much uncorrected remaining aberration to be corrected by the rear group lens system. On the other hand, if the v difference is less than 20, it is difficult to obtain the undercorrection for attaining the object.

The condition (5) indicates that under condition l the cemented lens consisting of the fifth lens and the sixth lens cemented together has almost no power. Condition (4) is of course characterized in that it is valid within the range of condition (5). When the lens system remarkably deviates from condition (4), then it also deviates condition (5). Accordingly, irrespective of plus or minus signs, with respect to} f I and| f the range of the condition (4) is appropriate, as is shown also in the examples. Condition (5) is originally intended for miniaturizing the objective and is characterized in that the resultant power of the fifth lens and the sixth lens is small. It is considered that the power of such degree as IF I F/0.3 will not disturb various aberration conditions. For miniaturization the thickness of the fifth lens and of the sixth lens naturally come into question. It is considered that an F l which is smaller than F/0.3 would be to some extent unsuited for the object of the present invention.

Condition (6) is closely related to condition (7) and suitably determines the amount which depends on correction of spherical aberration and coma at the 15th surface. When n n is larger than 0.4, correction of spherical aberration is apt to be excessive, and with respect to coma, in respect of light'rays of low incident ray height, correction is excessive in the direction in which the image height increases. When n, n is smaller than 0.15, through the whole system, the effect of the 15th surface, which has large negative spherical aberration, is apt to be lost. Even if correction is to be by means of another surface, it is difficult to do so with a single surface within the range in which the aberrations are not unfavorably influenced. Also, with respect to coma, the aberration is produced in the inverse direction to the aberration that is produced when n, n is larger than 0.4. I

Condition (7) is intended for compensation of the above-mentioned situation by means of another condition. 1f r is smaller than 0.55F, the effect is excessive, resulting in an aberration which would be produced when n, n is larger than 0.4.

Condition (8) is intended for correcting coma with respect to rays of low incident ray height of the bundle of light rays having comparatively large incident angle. 1f r is smaller than 0.7F, the result will be too much aberration in the direction of higher image height. 1f r is larger than 1.4F, the aberration is apt to be produced in the reverse direction. Compensation of this by means of another member is not desirable since it will influence also light rays having comparatively small incident angles.

Condition (9) is originally intended for correcting chromatic aberration, that is, for producing effective achromatism by means of the sixth lens and following lenses. 1f the 1 value of a negative lens indicated in this condition is smaller than 55, then the v value of the secnd lens (a positive lens) must be small. This increases ference of magnification is corrected with respect to large angles, it will be remarkably present with respect to small angles, leading to an undesirable result as a whole. Accordingly, in order to make better correction of chromatic difference of magnification with the positive lens of large 1 value, it is desirable that the negative lens not produce longitudinal chromatic aberration due to overcorrection. The conventional method is to use negative lenses of large v value. The remarkable feature of the present invention is, however, to excellently correct the chromatic difference of magnification by such an arrangement that each lens of the plurality of lenses constituting the'front lens group has a large 11 value and the intermediate group of lenses is placed in an undercorrected state.

The low aberration obtained for the wide angle lens system of FIGS. 1, 3 and 5 is a marked improvement over previous wide angle lens systems as demonstrated by the aberration curves of FIGS. 2, 4 and 6.

The data in the examples shown in the drawings are as follows:

TABLE 1 1334) ume) M) 03) (f8) Examplel 0.919F -1.F 44.98F 0.98F 1.05F

Example 2 0.918F 1.19F 10.11F 0.97F 0.97F Examp1e3 0.9186F 1.251= 8.15F 1.04F 1.00F

TABLE 11 EXAMPLE 1 F 100mm d-line Lens Length in Lens index of Abbes Surface mm mm Number refraction Number R1 519.231 111 11.06 1 1.64000 60.2 R2 138.498 11 22.12

R3 209.135 d2 37.50 2 1.51633 64.1 R4 757.390 14 0.72 R5 78.365 d3 8.99 3 1.64000 60.2 R6 49.066 13 24.04 R7 117.788 d4 8.99 4 1.64000 60.2 R8 58.350 14 20.67

R9 384.615 d5 31.25 5 1.63636 35.4 R10 -55.288 d6 31.25 6 1.58913 61.2 R11 619.439 15 14.42 R12 649.038 d7 10.58 7 1.58913 61.2 R13 106.296 16 0.48 R14 83.111 d8 16.83 8 1.58913 61.2 R15 -73.077 d9 7.69 9 1.81554 44.4

R17 192.308 117 7.21 10 1.51823 59.0 R18 78.832 18 0.48 R19 403.846 (111 6.73 11 1.76182 26.5 R20 108.806 19 8.17 R21 743.971 d1216.83 12 1.51190 58.2 R22 89.216

} TABLE 111 Table of Seidels Coefficients of Example 1 Lens s1 s2 s3 P 85 Surface R1 0.002 0.007 0.029 0.075 0.424 R2 -0.417 0.029 0.002 0.282 0.020 R3 0.231 0.067 0.020 0.163 0.053 R4 0.001 0.005 0.037 0.045 0.570 R5 0.677 0.046 0.003 0.498 0.034 R6 5.429 0.951 0.167 0.795 0.169 R7 1.235 0.320 0.083 0.331 0.107

0 R8 12.037 0.202 0.003 0.669 0.011 R9 0.438 0.363 0.300 0.101 0.165 R10 0.483 0.128 0.034 0.033 0.018 R11 -0.486 0.366 0.275 0.060, 0.162 R12 2.292 0.927 0.375 0.057 0.175 R13 6.503 1.191 0.218 0.349 0.104 R14 3.603 0.957 0.254 0.446 0.186

- R18 16.147 1.023 I 0.065 0.433 0.032 R19 0.064 0.111 0.191 0.107 0.145

cl-line index of refraction 1 .64000 d-line index of refraction 1 .64000 Abbes Number 60.2

Abbe's Number 60.2

R20 2.864 -1.271 0.564 R21 0.039 0.061 0.096 R22 16.469 0.068 0.000 SUM 4.317 0.371 0.047

TABLE IV EXAMPLE 2 Lens Length in Lens Surface mm mm Number R1 518,657 111 11.04 1 R2 138.308 11 22.09 R3 211.305 112 37.46 2 R4 726.730 12 0.72 R5 76.838 d3 8.98 3 R6 48.384 13 24.01 R7 121.471 d4 8.98 4 R8 59.271 14 20.65 R9 168.083 115 21.61 5 R10 74.331 d6 31.21 6 R11 229.587 15 14.41 R12 696.345 d7 10.56 7 R13 119.358 16 0.48 R14 83.019 118 16.81 8 R15 67.978 :19 7.68 9 R16 132.229 17 7.68 R17 192.095 1110 7.20 10 R18 77.808 18 0.48 R19 384.190 d11 6.72 11 R20 105.595 19 8.16 R21 743.149 1112 16. 12 R22 88.028

TABLE V Table of Seidel's Coefficients of Example 2 Lens S1 S2 S3 Surface R1 0.002 0.007 0.029 R2 -0.419 0.021 0.001 R3 0.228 0.072 0.023 R4 0.001 0.006 0.038 R5 0.721 0.054 0.004 R6 5.608 0.895 0.143 R7 1.171 0.341 0.099 R8 1 1.769 0.062 0.000 R9 0.046 0.113 0.282 R10 4.981 0.233 0.011 R11 0.001 0.013 0.177 R12 1.411 0.671 0.319 R13 4.601 0.985 0.211 R14 3.278 0.907 0.251 R15 22.353 0.554 0.014 R16 917 -0.472 0.243 R17 0.367 0.179 0.087 R18 15.618 0.993 0.063 R19 0.057 0.106 0.195 R20 2.875 1.301 0.589 R21 0.037 0.060 0.098 R22 15.993 0.105 0.001 SUM 3.720 0.487 0.019

TABLE VI EXAMPLE 3 F 100 mm Lens Length in Lens Surface mm mm Number R1 519.231 111 13.85 1 R2 130.205 11 40.86 R3 250.000 112 38.46 2 R4 569.697 12 0.24 R 81.731 113 8.99 3 R6 51.734 13 24.04 R7 121.154 d4 8.99 4* R8 60.657 14 23.08 R9 -173.077 115 19.23 5 R 80.288 d6 33.65 6 R11 -239.723 13.46 R12 3605.769 117 11.06 7 R13 113.405 16 0.24 R14 83.173 d8 16.83 8 R15 69.711 89 8.65 9 R16 131.757 17 8.65 R17 199.519 1110 9.61 10 R18 77.619 18 0.48 R19 353.365 1111 6.73 11 6 R20 109.566 19 9.61 R21 649.038 1112 19.23 12 1.51633 64.1 R22 97.328

TABLE V11 Table of Seidels Coefficients of Example 3 Lens s1 s2 s3 P 55 Surface R1 0.002 0.007 0.027 0.075 0.412 R2 0.416 0.054 0.007 0282 0.038 R3 0.202 0.082 0.033 0.136 0.069 R4 0.002 0.011 0.051 0.060 0.530 R5 0.763 0.068 0.006 0.477 0.043 R6 -5.897 0.795 0. 107 0.754 0.116 R7 1.366 0.354 0.092 0.322 0.107 R8 13.134 0.038 0.000 0.643 0.002 R9 0.038 0.101 0.265 0.197 0.180 R10 6.062 0.292 0.014 0.055 0.003 R11 0.000 0.001 0.160 0.161 0.164 R12 0729 0.435 0.259 0.010 0.161 R13 5.904 1.124 0.214 0.327 0.103 R14 3.876 0.990 0.253 0.446 0178 R15 24.559 0.625 0.016 0.1 13 0.003 R16 1.059 0.508 0.244 0.341 0.280 R17 0.379 0.179 0.084 0.171 0.120 R18 18.675 -0.915 0.045 0.493 0.024 R19 0.060 0.110 0.202 0.126 0.139 R20 2.667 1.196 0.536 0.407 0.423 R21 0.033 0.052 0.083 0.052 0.216 R22 14.571 0.107 0.001 0.350 0.003 SUM 4.052 0.459 0.012 0.129 0.263

-In tables 111, V and V11, the definitions of symbols are as follows:

S1 Spherical aberration S2 Coma S3 Astigmatism S5 Distortion P Petzval sum FIGS. 1, 3 and 5 show indicia d1 through dl2, d1 through d9 identifying the indicated dimensions and R1 through R22 identifying the indicated surfaces. The tables use these same indicia to identify the correspond- I ing dimensions and surfaces in FIGS. 1, 3 and 5.

' d-line Lens Length in Lens index of Abbes Surface mm mm Number refraction Number R1 519.231 111 11.06 1 1.64000 60.2 R2 138.498 11 22.12 R3 209.135 112 37.50 2 1.51633 64.1 R4 757.390 12 0.72 R5 78.365 d3 8.99 3 1.64000 60.2 R6 49.066 13 24.04 R7 117.788 114 8.99 4 1.64000 60.2 R8 58.350 14 20.67 R9 -384.615 d5 31.25 5 1.63636 35.4 R10 55.288 116 31.25 6 1.58913 61.2 R11 -619.439 15. 14.42 R12 649.038 117 10.58 7 1.58913 61.2 R13 106.296 16 0.48 R14 83.111 d8 16.83 8 1.58913 61.2 R15 73.077 d9 7.69 9 1.81554 44.4 R16 128.104 17 7.69 R17 192.308 d7 7.21 10 1.51823 59.0 R18 78.832 18 0.48 g R19 403.846 1111 6.73 11 1.76182 26.5 R20 108.806 19 8.17 R21 743.971 1112 16.83 12 1.51190 58.2 R22 89.216

F mm

and wherein having greatly improved aberrations, comprising a 10 group, 12 element lens wherein the lens elements have the following characteristics:

d-line Lens Length in Lens index of Abbe's Surface mm mm Number refraction Number R1 518.657 d1 11.04 1 1.64000 60.2 R2 138.308 11 22.09 R3 211.305 d2 37.46 2 1.51633 64.1 R4 726.730 12 0.72 R5 76.838 d3 8.98 3 1.64000 60.2 R6 48.384 13 24.01 R7 121.471 d4 8.98 4 1.64000 60.2 R8 59.271 I4 20.65 R9 -168.083 d5 21.61 5 1.51633 64.1 R10 74.331 d6 31.21 6 1.60342 38.0 R11 229.587 14.41 R12 696.345 d7 10.56 7 1.58913 61.2 R13 -119.358 16 0.48 R14 83.019 d8 16.81 8 1.58913 61.2 R15 67.978 d9 7.68 9 1.81554 44.4 R16 132.229 17 7.68 R17 192.095 d10 7.20 10 1.51823 59.0 R18 -77.808 18 0.48 R19 384.190 dll 6.72 11 1.76182 26.5 R20 105.595 19 8.16 R21 743.149 d12 16.81 12 1.51633 64.1 R22 88.028

F 100 mm.

and wherein lenses 5 and 6 and lenses 8 and 9 fonn doublets;

the lenses are numbered 1 through 12 from the object side;

F is the resultant focal length of the whole lens system;

F'l'2'---i is the resultant focal length of the first to the i-th lens;

fn is the focal length of the n-th lens; and

R, d and l in numbered succession refer to the surface radii, thickness and spacing, respectively.

3. A super wide angle photographic objective lens having greatly improved aberrations, comprising a 10 group, 12 element lens wherein the lens elements have the following characteristics:

. d-line Lens Length in Lens index of Abbe's Surface mm mm Number refraction Number R1 519.231 d1 13.85 1 1.64000 60.2 R2 130.205 11 40.86 R3 250.000 1.12 38.46 2 1.51633 64.1 R4 569.697 12 0.24 R5 81.731 d3 8.99 3 1.64000 60.2 R6 51.734 13 24.04 R7 121.154 d4 8.99 4 1.64000 60.2 R8 60.657 14 23.08 R9 173.077 d5 19.23 5 1.51633 64.1 R10 80.288 d6 33.65 6 1.62588 35.6 R11 -239.723 15 13.46 R12 3605.769 d7 11.06 7 1.58913 61.2 R13 113.405 16 0.24 R14 83.173 d8 16.83 8 1.58913 61.2 R15 69.711 119 8.65 9 1.81554 44.4 R16 131.757 17 8.65 R17 199.519 d10 9.61 10 1.51633 64.1 R18 77.619 l8 0.48 R19 353.365 d11 6.73 11 1.80518 25.5 R20 109.566 19 9.61 R21 649.038 d12 19.23 12 1.51633 64.1 R22 97.328

F mm

F 1234 -O.9186F and wherein lenses 5 and 6 and lenses 8 and 9 form doublets;

the lenses are numbered 1 through 12 from the object side;

F is the resultant focal length of the whole lens system;

F'l'2""i is the resultant focal length of the first to the i-th lens;

fn is the focal length of the ri-th lens; and

R, d and l in numbered succession refer to the surface radii, thickness and spacing, respectively.

t i t 4 t 

1. A super wide angle photographic objective lens having greatly improved aberrations, comprising a 10 group, 12 element lens wherein the lens elements have the following characteristics: d-line Lens Length in Lens index of Abbe''s Surface mm mm Number refraction Number R1 519.231 d1 11.06 1 1.64000 60.2 R2 138.498 l1 22.12 R3 209.135 d2 37.50 2 1.51633 64.1 R4 -757.390 l2 0.72 R5 78.365 d3 8.99 3 1.64000 60.2 R6 49.066 l3 24.04 R7 117.788 d4 8.99 4 1.64000 60.2 R8 58.350 l4 20.67 R9 -384.615 d5 31.25 5 1.63636 35.4 R10 -55.288 d6 31.25 6 1.58913 61.2 R11 619.439 l5 14.42 R12 649.038 d7 10.58 7 1.58913 61.2 R13 106.296 l6 0.48 R14 83.111 d8 16.83 8 1.58913 61.2 R15 -73.077 d9 7.69 9 1.81554 44.4 R16 128.104 l7 7.69 R17 -192.308 d7 7.21 10 1.51823 59.0 R18 -78.832 l8 0.48 R19 403.846 d11 6.73 11 1.76182 26.5 R20 108.806 l9 8.17 R21 743.971 d12 16.83 12 1.51190 58.2 R22 -89.216 F 100 mm F1.2.3.4 -0.919F F1.2....6 -1.F F5.6 44.98F f5 0.98F f6 - 1.05F and whereIn lenses 5 and 6 and lenses 8 and 9 form doublets; the lenses are numbered 1 through 12 from the object side; F is the resultant focal length of the whole lens system; F.1.2.....i is the resultant focal length of the first to the ith lens; fn is the focal length of the n-th lens; and R, d and l in numbered succession refer to the surface radii, thickness and spacing, respectively.
 2. A super wide angle photographic objective lens having greatly improved aberrations, comprising a 10 group, 12 element lens wherein the lens elements have the following characteristics: d-line Lens Length in Lens index of Abbe''s Surface mm mm Number refraction Number R1 518.657 d1 11.04 1 1.64000 60.2 R2 138.308 l1 22.09 R3 211.305 d2 37.46 2 1.51633 64.1 R4 -726.730 l2 0.72 R5 76.838 d3 8.98 3 1.64000 60.2 R6 48.384 l3 24.01 R7 121.471 d4 8.98 4 1.64000 60.2 R8 59.271 l4 20.65 R9 -168.083 d5 21.61 5 1.51633 64.1 R10 74.331 d6 31.21 6 1.60342 38.0 R11 -229.587 l5 14.41 R12 696.345 d7 10.56 7 1.58913 61.2 R13 -119.358 l6 0.48 R14 83.019 d8 16.81 8 1.58913 61.2 R15 -67.978 d9 7.68 9 1.81554 44.4 R16 132.229 l7 7.68 R17 -192.095 d10 7.20 10 1.51823 59.0 R18 -77.808 l8 0.48 R19 384.190 d11 6.72 11 1.76182 26.5 R20 105.595 l9 8.16 R21 743.149 d12 16.81 12 1.51633 64.1 R22 -88.028 F 100 mm. F1.2.3.4 -0.918F F1.2.... 6 -1.19F F5.6 10.11F f5 -0.97F f6 0.97F and wherein lenses 5 and 6 and lenses 8 and 9 form doublets; the lenses are numbered 1 through 12 from the object side; F is the resultant focal length of the whole lens system; F.1.2....i is the resultant focal length of the first to the i-th lens; fn is the focal length of the n-th lens; and R, d and l in numbered succession refer to the surface radii, thickness and spacing, respectively.
 3. A super wide angle photographic objective lens having greatly improved aberrations, comprising a 10 group, 12 element lens wherein the lens elements have the following characteristics: d-line Lens Length in Lens index of Abbe''s Surface mm mm Number refraction Number R1 519.231 d1 13.85 1 1.64000 60.2 R2 130.205 l1 40.86 R3 250.000 d2 38.46 2 1.51633 64.1 R4 -569.697 l2 0.24 R5 81.731 d3 8.99 3 1.64000 60.2 R6 51.734 l3 24.04 R7 121.154 d4 8.99 4 1.64000 60.2 R8 60.657 l4 23.08 R9 -173.077 d5 19.23 5 1.51633 64.1 R10 80.288 d6 33.65 6 1.62588 35.6 R11 -239.723 l5 13.46 R12 3605.769 d7 11.06 7 1.58913 61.2 R13 -113.405 l6 0.24 R14 83.173 d8 16.83 8 1.58913 61.2 R15 -69.711 d9 8.65 9 1.81554 44.4 R16 131.757 l7 8.65 R17 -199.519 d10 9.61 10 1.51633 64.1 R18 -77.619 l8 0.48 R19 353.365 d11 6.73 11 1.80518 25.5 R20 109.566 l9 9.61 R21 649.038 d12 19.23 12 1.51633 64.1 R22 -97.328 F 100 mm F 1.2.3.4 -0.9186F F1.2....6 -1.25F F 5 6 8.15F f5 -1.04F f6 1.00F and wherein lenses 5 and 6 and lenses 8 and 9 form doublets; the lenses are numbered 1 through 12 from the object side; F is the resultant focal length of the whole lens system; F.1.2....i is the resultant focal length of the first to the i-th lens; fn is the focal length of the n-th lens; and R, d and l in numbered succession refer to the surface radii, thickness and spacing, respectively. 